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quest to 400hp

Joined
5 September 2000
Messages
684
Location
PA
Just want to share new results. Another dyno and 400hp still not reached :( After I came back from dyno I found out that my external wastegate vacuum hose that goes to turbocharger snap off from fitting and that is why I could not raise boost. But this dyno is good example of different turbochargers and different power band. Almost same boost. On old turbocharger it was 9psi on new it was 9.9psi.

My old turbocharger housing was .63 a/r (good low end, bad top end result, car was more fun to drive once you step on the pedal it would just take off like on NOS)
New turbocharger housing is .83 a/r (bad low end, high top end result, it opens up on highway nice but you have to wait for the power)

This time I run 360hp and 314tq, back to back after few runs. I raise boost to 11psi after fixing the vacuum hose and the car was wild, but have to dyno again to see it on paper. I have all my components beefed up so I can hold up to 14psi but I'm taking it easy. Boost is very addictive :)

Dave
 

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Ill be at turbotrix on tuesday with my NSX...
 
you should really try a much larger turbo if you want the 400 mark. A/R is obviously important but you seem to be using a pretty small turbo both times, it seems like it was choking last time (trying to move more air than it can) and not it seems like you have alittle lag issue...go back to the .63 AR but use a bigger unit, like a t-60 or t-61. it will end up splittling the 2 you have now below 5K and have way more up top. I think the dip you see after 7K is your factory intake manifold. this is something that i think we all need to work on next. port and polish is great but the mani design could be WAY WAY WAY better.

nice project by the way.....
 
winreboot said:
Boost is very addictive :)

Yes, it is insanely addictive, I hope you don't get to a point where you will be scared to drive the car. T61 or PT61 will be a very good choice for your next turbo. They spool up very quick for mid size turbo.

Congratulations! techinically you are at well over 400hp at crank, can you please give a brief driving impression write up?
 
Just thinking out loud here but, I have noticed that every dyno plot I have ever seen for the NSX has a massive tapering or at least flattening in power after 7K. I know that we have all been told that our car has an 8K (or about) redline and that the engine makes most power up top but looking at the dyno plots it seems as if this is not entirely true. It seems as if even an Integra or rsx make more power up high that the nsx engine (speaking in % ratio of course).

With this in mind it seems to make since why all of the FI answers have always seemed to be somewhat lacking in the actual amount of maximum HP.

The car just runs out of steam right when we are expecting it to come alive.

The math really seems to support this also….. Say you want 350 hp (crank, just like factory rates the car) this would be an increase of 27%, which using conventional formulas would mean we would need approximately 4 PSI to reach this HP goal.
350 hp = 520 CFM through the engine. But when even when using this formula and the 27% you only come up with about 485 CFM which is only 324 HP !!!! Granted this would only be 4 psi and it is pretty close but….

Now if we use the usable RPM number of 7000 you come up with 425 CFM which is really only 283 HP @ 4psi. This seems closer to what everyone is seeing.

The car is supposed to already flow 384 CFM @ 8K rpm which is about 256 HP which sounds about right from most of the Dyno’s I have seen posted. This number gets silly using the 7k rpm number, 335CFM @ 224 HP. (This 7K issue seems to go away w/ the CTSC on the dyno)

So I guess my question is this, if the math is there, engine size X rpm X efficiency and it is coming up @ 256 +/-. How and why is everyone using 275 HP as a starting point and baseline for how they build or design or rate a FI system?

I mean if we use the numbers above as a starting point, 256 hp and 384 cfm and look for say the same 350 HP then we would need to increase power by 36% which would then mean we need a little over 5.2 PSI. Using the magic 8K rpm this would give ya 520 CFM or 346 HP. Using the 7K rpm number you come up with 455 CFM or 303 hp. isn’t this in the neighborhood of where all the CTSC cars seem to be? And are they running 6 psi…?

I guess I really don’t have a point…  I am just wondering where the math is wrong..? Which part doesn’t seem to make cense? (As I read this post not much of it makes cense, sorry) I mean the math doesn’t lie and using a 3.0 engine size the car should only have 256 HP. Slapping a SC on it and getting 50 extra HP seems like a good deal to me, forgetting cost but why are the numbers so far off? I have even tried this exercise with higher than a 90% engine efficiency rating and they are still screwed up!!?? I guess what I am asking is what number do you all use for your baseline to decide if you have made improvements or not? The 275 hp number from acura or something else?

I guess this is an indication of my addiction :)
 
I don't know what mods you have, but perhaps aftermarket cams designed for FI and a larger intake manifold will help keep the power from tapering off.
 
winrebot has a few mods but it seesm to be a very very common issue on all cars. i could be wrong ofcourse but it seems this way to me.

cams could help but at the expense of low end power which ours lack anyway. :(
as far as the larger intack mani, yes i agree, know where i could find one :) I am going to play with maing some 10mm phenolic spacers which would insulate intake manifold from heat conduction through the heads, leading to lower intake air temps -extends the intake runner lengths for better low end torque. and poerting and polishing the HELLL out of the TB and mani. see what happens i guess.

as far as what mods i have...none yet, obviously going to build a turbo setup though
 
GJ told me that with Fi (esp. high boost turbo) the intake manifold porting etc. isn't that important. That stuff he said is more pertainent in NA situations. Remember you are STUFFING the air in fast and pressurized, its going in no matter what.
The right turbo makes all the difference, I don;t know what the right one is for you but the T04E is what mine has and GJ & TurboNSX & LEN3.8
 
Don't get me wrong the car runs nice, and dyno is only 3rd gear acceleration. When lunching from stop it will move and keep in boost, and if I would not daily drive the other turbocharger I would most likely not know the difference. I'll most likely change the trim on the compressor wheel later, after tasting the power on low end know what it is. I like to work on the turbo stuff and it keeps me occupied on the weekends :)

Engine is basically 9:1 compression, oem sleeves, ported heads, RC550's, walbro fuel pump, Comptech PGII etc... On electronics side aem ems, dual widebands, HKS boost controller etc ...

If you are in NJ area and need AEM tuning, turbo trix is the place to do it at. They are just the best, and tune the car in no time. They make the car run like OEM but on steroids :)

On different subject, did any one remove the EGR valve on FI engine ?? (I think it routes exhaust gases back to intake under 3k rpm's for emission purposes ?) I guess we don't need that after going FI and it just heats up the intake ?
 
brandonson said:
I think a GT35R will solve your problem. Spools up fast and has GREAT top end power.


Tis true, tis true. My turbo is very similar.... well half of it is close to a gt35, the other half is a tad larger. Fast spool-up and a top-end that I'm scared to test.
 
GJ told me that with Fi (esp. high boost turbo) the intake manifold porting etc. isn't that important. That stuff he said is more pertainent in NA situations. Remember you are STUFFING the air in fast and pressurized, its going in no matter what.
The right turbo makes all the difference, I don;t know what the right one is for you but the T04E is what mine has and GJ & TurboNSX & LEN3.8

Not true...I made went from 360 rwhp to 400 when switching to a larger custom intake manifold (did lose some low end).
 
The IAT is hot, hot, hot…. 160-180F running air/air intercooler. Will be converting to air/water this weekend if it's build.

The nsx or any other turbo car does not run out off steam at the end of the dyno run, is being controlled by boost controller.

Any NA or supercharged car the line goes straight up and the top HP will be at the end of the dyno graph (8K rpms)

Any Turbo car the line graph will hit one point and then start to decline towards the end together with TQ, because the desired boost was reached. TQ goes down after it because the wastegate bypasses exhaust gasses and it looses back pressure. The RPM's goes higher but boost is controlled by boost controller and it stays the same, so the line will go down after getting desired boost.

To make dyno graph look like NA or supercharged one, only ONE turbine would do that for desired application. I don't know the right a/r housing or the compressor that will do it. So, one will have to know what boost they want and what HP then custom turbine would have to be made, and it should hit the bulls eye at 8k rpm's. All turbochargers will make boost, but all have + and - to them. There is excellent explanations of the turbochargers in Super Street Magazine it explains the different housings, a/r, wheels, T technology, and GT turbocharger technology etc ….

Dave
 
winreboot said:
The IAT is hot, hot, hot…. 160-180F running air/air intercooler. Will be converting to air/water this weekend if it's build.


Are you measuring that with the stock sensor post-throttle body or did you install an aftermarket sensor pre-throttle body?
 
winreboot said:
It is the stock OEM air temp sensor that is on top of the intake manifold.

If your car was stationary on a dyno for all those runs, 160-180 is not that out of the ordinary. With normal driving speeds and proper airflow through your aftercooler core, I'm sure the IAT's are much lower on the street.

I use the OEM sensor as well. Typically during warm weather months my IAT's on the street are 110-115. The highest I see are in the 160-180 range, but that only occurs when I'm sitting in traffic for a prolonged period. As soon as I get moving again the temps come right down. I have an air/water system.

If you measure pre throttle-body, the temps are significantly lower.
 
HAHAHAHAHA 115-118 on the street....thats what the air temp is here add a car and some black top and you are 140+ before a turbo :)
 
I understand what you are saying about boost control and I think you have misinterpreted what I was saying. I feel the engine does not flow air as efficiently above 7K as we would like too, or where lead to believe.

as far as understanding how to read when boost ls vented... I would like to beleive that most people who are reading/posting the FI forum are at least up to par with this. If you notice, most people who post in this forom seem to concentrate on it, I dor one dont even read the other forums...maybe once a week, if at all.
 
xLusi0n said:
Not true...I made went from 360 rwhp to 400 when switching to a larger custom intake manifold (did lose some low end).

I agree with this statement. (Not that you need my approval, as you have the results to prove it)

IMHO, a good intake manifold is very important for a FI engine, and this has been proven many times. Intake manifold design for a NA engine is very tricky, as it really has to be made to suit the exact powerband requirements of the engine. With a FI engine, the loss in low end torque is barely noticeable compared to the huge gains that can be had in the mid-high end.
Also, making use of the inertia of the intake air pulsing is less important with FI as usually a good turbo setup will have a positive pressure relationship (boost is higher than exh pressure). This is far more effective than the small pressure increases available from tuned length/diameter runners and plenum volume on a NA engine.

Basically, with a high power FI engine, good flow (as opposed to tuned length, etc.) becomes the main priority in the intake manifold.

An interesting point with the positive pressure relationship turbo system is that it works very well with big camshafts. Some of you may remember back to the days when turbocharging VTEC engines was in its infancy. Many people had better results by disabling the VTEC. This is because the turbocharger was too small, causing very high exhaust pressure. This causes problems with the overlap on the big VTEC lobe. During the overlap stage, exhaust pressure is higher than boost pressure to the point that the inertia effect in the intake and exhaust systems can't properly scavenge the combustion chamber.

About two years ago, a turbo S2000 came to my shop supposedly with a problem with the VTEC. The car was using a F-conV and apparently would not switch VTEC properly. They had even tried using aftermarket VTEC controllers to cure the problem to no avail. They decided to fit a Motec (good idea) and came to me as I was the first person to fit Motec to a S2000 so they figured I might be able to help out.
I had a look at the turbo setup (they got it from the US) and as soon as I saw the manifold and turbo I knew what was wrong. They didn't believe me so we went ahead with the Motec anyway. Well, long story short, they eventually changed the turbo and manifold and magically the VTEC problem went away. :biggrin: Oh, the turbo was changed to a GT35R BTW.

Oh, and I use TODA spec C cams with my 10500rpm turbo Civic. :cool:

We make billet CNC machined intake manifolds at work, but unfortunately I doubt we will make any for the NSX (one of the drawbacks of having such an exclusive car, even the boss can't have one :frown: )

Anyway, I guess this is all just talk untill I turbo my NSX. I better get on with it!!
 
01blacks4 said:
Just thinking out loud here but, I have noticed that every dyno plot I have ever seen for the NSX has a massive tapering or at least flattening in power after 7K. I know that we have all been told that our car has an 8K (or about) redline and that the engine makes most power up top but looking at the dyno plots it seems as if this is not entirely true.


http://www.nsxprime.com/forums/showthread.php?t=34136&highlight=peiserg

that's an old thread where I posted a couple dyno graphs, as well as emvanderpool (ctsci think) and both of ours make increasing power past 7500
 
again as i said,,,except for a FI car it seems this way.

i can only go by the 12 cars i have seen dyno plots for, each laid over each other on the dyno itself....
 
I finally took some pics of the 4G63 (DSM?) manifolds we are making.

I would love to make some for the NSX, but doubt there would be a big enough market. What do you guys think?
 

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